1. Field of the Invention
The present invention relates to a heater control apparatus for controlling a heater section of a sensor and to a sensor control system including the sensor and heater control apparatus.
2. Description of the Related Art
A conventionally known example of a sensor having a heater section is a gas sensor which detects the concentration of a specific gas contained in exhaust gas, such as an oxygen sensor or a nitrogen oxide (NOx) sensor. These gas sensors include a sensor element section which is formed of a solid electrolyte body mainly made of zirconia, and a heater section which heats the sensor element section. The heater section is controlled by a heater control apparatus so as to bring the sensor element section into an activated state. For example, Patent Document 1 discloses a heater control apparatus which controls the amount of electric current supplied to a heater section by controlling its duty ratio.
[Patent Document 1] Japanese Patent Application Laid-Open (kokai) No 2002-257779